\begin{table}[htbp!] \centering \begin{threeparttable}                                 \begin{tabular} {l c c c c c} \toprule                                 \caption{Determinants of nudge adoption (robustness)\label{tab:reg_robust} }                                 & Baseline & Robust SEs & \multicolumn{3}{c}{Robustness to marginal cases} \\ \cmidrule(lr){2-2} \cmidrule(lr){3-3} \cmidrule(lr){4-6}                                 
Dep. Var.: Nudge adopted (0/1, OLS)&        (1) &         (2)&         (3)&         (4)&         (5)\\
\hline
Max $ t\geq1.96$    &       -0.03&       -0.03&       -0.06&        0.06&        0.03\\
                    &      (0.08)&      (0.10)&      (0.09)&      (0.10)&      (0.10)\\
Max treatment effect (10pp.)&        0.10&        0.10&        0.11&        0.02&        0.02\\
                    &      (0.07)&      (0.07)&      (0.07)&      (0.05)&      (0.05)\\
City staff retained &        0.07&        0.07&        0.04&        0.02&       -0.02\\
                    &      (0.08)&      (0.09)&      (0.09)&      (0.07)&      (0.07)\\
Above-median city population&        0.06&        0.06&        0.05&        0.03&        0.02\\
                    &      (0.08)&      (0.08)&      (0.09)&      (0.09)&      (0.09)\\
What Works Cities certified&        0.14&        0.14&        0.18&        0.06&        0.11\\
                    &      (0.11)&      (0.11)&      (0.12)&      (0.12)&      (0.13)\\
Communication pre-existed&        0.52&        0.52&        0.56&        0.40&        0.45\\
                    &      (0.13)&      (0.12)&      (0.13)&      (0.18)&      (0.18)\\
\textit{Mechanism} \\ %&        ref.&        ref.&        ref.&        ref.&        ref.\\
\hspace{1em}Simplification \& information&        0.03&        0.03&        0.04&        0.10&        0.11\\
                    &      (0.10)&      (0.10)&      (0.09)&      (0.06)&      (0.07)\\
\hspace{1em}Personal motivation&       -0.12&       -0.12&       -0.15&       -0.11&       -0.14\\
                    &      (0.12)&      (0.10)&      (0.11)&      (0.07)&      (0.07)\\
\hspace{1em}Social cues&       -0.08&       -0.08&       -0.09&       -0.10&       -0.13\\
                    &      (0.08)&      (0.10)&      (0.09)&      (0.10)&      (0.10)\\
Constant            &        0.05&        0.05&        0.10&        0.03&        0.07\\
                    &      (0.15)&      (0.14)&      (0.16)&      (0.12)&      (0.12)\\
\hline
Average adoption rate&        0.27&        0.27&        0.29&        0.15&        0.16\\
Dropping marginal non-adopts&            &            &$\checkmark$&            &$\checkmark$\\
Dropping verbal-only adopts&            &            &            &$\checkmark$&$\checkmark$\\
Number of trials    &          73&          73&          69&          62&          58\\
Number of cities    &          30&          30&          29&          29&          27\\
$ R^2$              &        0.38&        0.38&        0.41&        0.37&        0.42\\
\bottomrule \end{tabular}                         \begin{tablenotes} \footnotesize                         \item Standard errors (shown in parentheses) are clustered at the city level except in Column 2,                                         which provides heteroskedastic-robust standard errors.                                 Baseline replicates Column 4 of Table 2.                                 See Appendix D for details on marginal non-adoption and verbal-only adoption cases.                         \end{tablenotes} \end{threeparttable} \end{table}
